1. Field of the Invention
The present invention relates to a single-electron transistor, and more particularly, to a single-electron transistor using nanoparticles.
2. Description of the Related Art
A single-electron transistor is a device that uses one electron to control a current by Coulomb blockade. The Coulomb blockade means a phenomenon that tunneling of an electron into a dot is blocked by a Coulomb repulsive interaction of it with another electron previously present in the dot.
Generally, current-voltage characteristics of a tunnel junction having a size of less than 100 nm and an appropriate resistance level do not follow Ohm's law. Rather, a current generated by tunneling of an electron at a low voltage approximates to zero. This phenomenon is generated by an electrostatic interaction of a tunneling electron and a charged medium. A theory based on quantum mechanics explains the phenomenon (for example, see Likharev et al., (1986)) and this phenomenon was first observed in an artificially formed micro-junction in 1987.
According to the above phenomenon, a single-electron transistor can be operated by one electron at less than a predetermined temperature. Here, the “predetermined temperature” means a temperature at which a thermal energy (KBT) is less than an electrostatic energy (e2/C) required for charging one electron in a junction of the single-electron transistor, i.e., a temperature satisfying the following equation 1:                     T        ⪡                              e            2                                              K              B                        ×            C                                              Equation        ⁢                                  ⁢        1            
wherein KB is Boltzmann constant (1.38×10−23 J/K). An electrostatic capacitance (C) is proportional to the size of a channel. In this regard, in order to observe the Coulomb blockade phenomenon at a desired temperature, the size of a channel must be reduced.
In a conventional single-electron transistor, a channel is formed to a narrow width by photolithography or e-beam lithography. However, with respect to the photolithography, it is difficult to form a small channel enough to be used at room temperature. The e-beam lithography can allow for the formation of a relatively small-sized channel, but is not suitable for commercial applications requiring mass production.